Compositions comprising boron compounds and polyphenyl thioethers

ABSTRACT

COMPOSITIONS COMPRISING POLYPHENYL THIOETHERS, POLYPHENYL ESTER-THIOETHERS OR MIXTURE THEREOF AND A DIPHENYLBORINIC ANHYDRIDE EXHIBIT IMPROVED CORROSIVENESS TOWARD COPPER AND SILVER WITHOUT LOSS OF OXIDATIVE STABILITY. SUCH COMPOSITIONS ARE USEFUL AS FUNCTIONAL FLUIDS.

United States Patent 3,751,368 COMPOSITIONS COMPRISING BORON COM- POUNDS AND POLYPHENYL THIOETHERS Frank S. Clark and Loren W. Bannister, St. Louis, Mo., assignors to Monsanto Company, St. Louis, Mo. N0 Drawing. Filed July 29, 1971, Ser. No. 167,466 Int. Cl. C09k 3/00 US. Cl. 25278 9 Claims ABSTRACT OF THE DISCLOSURE Compositions comprising polyphenyl thioethers, polyphenyl ethers-thioethers or mixtures thereof and a diphenylborinic anhydride exhibit improved corrosiveness toward copper and silver without loss of oxidative stability. Such compositions are useful as functional fluids.

This invention relates to compositions comprising polyphenyl thioethers, polyphenyl ethers-thioethers or mixtures thereof, containing from 3 to 8 aromatic groups and a corrosion inhibiting amount of a diphenylborinic anhydride. The compositions of this invention are useful as functional fluids.

Polyphenyl thioethers and polyphenyl ether-thioether combinations have found wide application as functional fluids due to their excellent thermal stability and lubriclty. For example they have been found to be valuable as hydraulic fluids and as lubricants in motor operation, particularly in jet engines, and as heat transfer agents. Two of the most rigorous demands on fluids are made by jet aircraft hydraulic systems and jet engine lubrication systems. For example, as the speed and altitude of operation of jet powered aircraft increases, lubrication problems also increase because of higher operating temperatures and higher bearing pressures resulting from the increased thrust needed to obtain higher speeds and altitudes. Thus, the service conditions encountered by functional fluids become increasingly severe, and therefore, the useful life of such fluids is shortened.

The useful life of any lubricant or hydraulic fluid can be adjudged on the basis of many criteria such as the extent of viscosity increase, the extent of corrosion to metal surfaces in contact with the lubricant and the extent of engine deposits. Those skilled in the art have found various ways to improve lubricants and to thus retard or prevent the effects which shorten the useful life of a lubricant. Thus, for example, small amounts of other materials, or additives, can be added to lubricants in order to affect one or more of the properties of the base lubricant. However, it is ditiicult, especially as operating temperatures are increased, to find additives which will still perform the function for which they are added and yet not inject other problems.

Therefore, an object of this invention is to extend the useful life of polyphenyl thioethers, polyphenyl etherthioethers or mixtures thereof by reducing their corrosivity toward certain metals without adversely affecting oxidative stability of the ethers.

These and other objects will become evident upon consideration of the following specification and examples.

The above and other objects of this invention are carried out by admixing polyphenyl thioethers, polyphenyl etherthioethers or mixtures thereof with a corrosion inhibiting amount of a diphenylborinic anhydride. The ether-boron compositions of this invention exhibit reduced corrosiveness toward metals without an adverse effect on oxidative stability of the base ether and thus have an extended service life even under the severe conditions encountered in jet engines and other devices operating at temperatures of the order of 600 F. The compositions exhibit markedly reduced corrosion toward copper and silver.

The improved compositions of this invention comprise a major amount of an ether base fluid of the formula wherein R is phenyl, alkyl-substituted phenyl wherein the alkyl is of not more than 4 carbon atoms, alkoxy-substituted phenyl wherein the alkoxy is of not more than 4 carbon atoms or halogenated phenyl wherein the halogen is bromine, fluorine or chlorine, R is phenylene, alkyl or alkoxy-substituted phenylene wherein the alkyl contains no more than 4 carbon atoms or halogenated phenylene wherein the halogen is fluorine, bromine or chlorine, and Y is selected from oxygen and sulfur but at least one of the Ys is sulfur and a is an integer having a value of 1 to 6 and a corrosion inhibiting amount of at least one diphenylborinic anhydride of the formula (ITQt t D.

wherein R is alkyl of not more than 4 carbon atoms, halogen (Cl, Br and F), alkoxy of not more than 4 carbon atoms, haloalkyl of not more than 4 carbon atoms and 3 halogen atoms (Cl, Br and F), haloalkoxy of not more than 4 carbon atoms and 3 halogen atoms (Cl, Br and F), phenoxy, phenylmercapto or N0 R is halogen (Cl, Br and F) or alkyl of not more than 4 carbon atoms, n is an integer of 0 to 3 and m is an integer of 0 to 2.

Representative groups for R in the above formula include halogen (Cl, Br and F), N0 phenoxy, thiophenoxy, alkyl such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl and t-butyl, alkoxy such as methoxy, ethoxy, butoxy, haloalkyl such as chloromethyl, bromomethyl, chloroethyl, bromoethyl, trichloromethyl, tribromornethyl, trifluoroethyl, dichloroethyl, chloro-n-propyl, bromo-n-propyl, bromo-n-butyl, bromo-tert-butyl, 1,3,3- trichlorobutyl and 1,3,3-tribromobutyl and haloalkoxy such as chloromethoxy, 1,2-dichlorobut0xy and fluoropropoxy. Representative groups for R include the halogen and alkyl listed above for R.

Representative boron compounds of the above formula include diphenylborinic anhydride di (3-methoxyphenyl)borinic anhydride di(4-n-butylphenyl)borinic anhydride di(2,4-dimethylphenyl)borinic anhydride di(4-methoxyphenyl)borinic anhydride di(4-chloromethylphenyl)borinic anhydride di 3-fiuoromethylphenyl borinic anhydride di(4-trifluorornethylphenyl)borinic anhydride di 4-chlorophenyl borinic anhydride di 2,4-dichlorophenyl borinic anhydride di 3-fluorophenyl borinic anhydride di(4-phenoxyphenyl)borinic anhydride di(4-nitrophenyl)borinic anhydride di(4-phenylmercaptophenyl)borinic anhydride di 2-fluoro-4-methylphenyl borinic anhydride di(2-methyl-4-chlorophenyl )borinic anhydride di 2-chloro-4-phenoxyphenyl borinic anhydride The amount of boron compound employed in the compositions of this invention can range from about 0.01 to about 1.5% by Weight. It is preferred to employ the acids in the compositions of this invention in amounts of from about 0.05 to about 1.5% by weight based upon the total composition.

The polyphenyl thioethers employed in the composition of this invention have from 3 to 8 benzene rings and from 1 to 7 sulfur atoms with the sulfur atoms joining the benzene rings in chains as ether linkages.

The term polyphenyl thioether as used herein means a compound or physical mixture of compounds wherein all of the Ys in the above formula are sulfur. The term polyphenyl etherthioether" as used herein means compounds or physical mixtures of compounds wherein at least one but not all of the Ys in the above formula is sulfur.

The compositions of this invention contain a maior amount of the polyphenyl thioether or polyphenyl etherthioether base stock, i.e., at least 50% by weight of the total composition comprises an ether. It is preferred that at least 60% by Weight of the composition be an ether base stock and even more preferred that at least 85% by weight of the total composition comprise an ether.

Illustrations of the alkyl-substituents present in the phenyl and phenylene groups of the ethers are, for example, methyl, ethyl, propyl, butyl and the like. Illustrations of the alkoxy-substituents are, for example, methoxy, ethoxy, propoxy, butoxy and their isomers.

The compositions of this invention can also contain from 0.01 to 10% by Weight of the total composition of a dialkyl hydrogen phosphite extreme pressure additive. The dialkyl hydrogen phosphites useful are those wherein the alkyl groups contain from 1 to 12 carbon atoms. The alkyl groups are for example, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, hexyl, decyl, isodecyl, dodecyl and the like.

Illustrative of the polyphenyl thioethers which can be employed as base stocks for the compositions of this invention are the bis(phenylmercapto)benzenes. For example m-bis (phenylmercapto benzene o-bis phenylmercapto) benzene p-bis phenylmercapto)benzene bis( m-phenylmercaptophenyl) sulfide bis o-phenylmercaptophenyl sulfide bis (p-phenylmercaptophenyl sulfide (m-phenylmercaptophenyl) (o-phenylmercaptophenyl) sulfide p-phenylmercapto-m'-phenylmercapto diphenyl sulfide o-bis (o-phenylrnercaptophenylmercapto benzene p-bis (p-phenylmercaptophenylmercapto benzene p-bis (o-phenylmercaptophenylmerc apto benzene p-bis (m-phenylmercaptophenylmercapto benzene m-bis (p-pheuylmercaptophenylmercapto benzene o-bis (p-phenylmercaptophenylmereapto benzene and the like and mixtures thereof.

Illustrative of the mixed polyphenyl ether-thioether compounds which can be employed as base stocks in the compositions of this invention are, for example,

o-phenylmercapto-m-phenoxy benzene p-phenylmercapto-p-phenoxy benzene m-phenoxy-p-phenylmercapto benzene o-phenylmercapto-p'-phenoxydiphenyl sulfide o-phenylmercapto-m'-phenoxydiphenyl sulfide o-phenoxy-m-phenylmercaptodiphenyl sulfide m-phenoXy-p'-phenylrnercaptodiphenyl sulfide o-phenoxy-p'-phenylmercaptodiphenyl sulfide p-phenoxy-p'-phenylmercaptodiphenyl sulfide o-phenoxy-o'-phenylrnercaptodiphenyl sulfide o,o'-bis(phenylmercapto) diphenyl ether o-phenylmercapto-m-phenylmercaptodiphenyl ether o-phenylmercapto-p-phenylmercaptodiphenyl ether m-(m-phenylmercaptophenylmercapto) (m-phenoxyphenylmercapto)benzene [m-(m-phenylmercaptophenylmercapto)phenyl] [m-(mphenoxyphenylmercapto)phenyl] sulfide 3-(m-phenylmercaptophenylmercapto)-3'-(m-phenylmcrcaptophenoxy)diphenyl sulfide 3 3 '-bis m-phenylrnercaptophenylmercapto) diphenyl ether 3 m-phe nylmercaptophenylmerc apto) -3 (m-pheonxyphenoxy)diphenyl sulfide 4-(m-phenylmercaptophenylmercapto)-4-(m-phenylmercaptophenoxy)diphenyl ether 3-(m-phenylmercaptophenylmercapto)-3'-(m-phenoxyphenylmercapto) diphenyl ether 4,4'-bis(m-phenylmercaptophenoxy)diphenyl sulfide 4,4'-bis(rn-phenoxyphenylrnercapto)diphenyl sulfide 3- m-phenoxyphenylmercapto) -3-(mphenylmercaptophenoxy)diphen.yl sulfide 3.3-bistm-phenylmercaptophenoxy)diphenyl ether 4-(m-phenylmercaptophenylmercapto)-4'-(m-phenoxyphenoxy)diphenyl ether 3- p-phenylmercaptophenoxy -3 p-phenoxyphenoxy) diphenyl sulfide 3-(m-phenylmercaptophenoxy)-3-(m-phenoxyphenylmercapto(diphenyl ether 3,3'-bis(rn-phenoxyphenylmercapto)diphenyl ether and 3- m-phenoxyphenylmercapto -3 (m-phenoxyphenoxy) diphenyl sulfide.

In addition to the foregoing compounds, the phenyl and phenylene of such compounds can contain substituents, such as alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms and halogen such as chlorine, bromine and fluorine. Examples of such compounds are as follows:

4,4-bis(m-tolylmercapto)diphenyl ether 3,3-bis(m-tolylmercapto)diphenyl ether 2,4'-bis(m-tolylrnercapto)diphenyl ether 3,4'-bis(m-tolylmercapto)diphenyl ether 3,3-bis(p-tolylmercapto)diphenyl ether 3,3-bis(xylylmercapto)diphenyl ether 4,4'-bis(xylylmercapto)diphenyl ether 3,4'-bis(xylylmercapto)diphenyl ether 3,4-bis(m-isopropylphenylmercapto)diphenyl ether 3,3-bis(rn-isopropylphenylmercapto)diphenyl ether 2,4'-bis(m-isopropylphenylmercapto)diphenyl ether 3,4'-bis(p-tert-butylphenylmercapto)diphenyl ether 4,4'-bis (p-tert-butylphenylmercapto) diphenyl ether 3,3'-bis(p-tert-butylphenylmercapto)diphenyl ether 3 ,3'-bis 2,4,-di-tert-butylphenylmercapto diphenyl ether 3,3'-bis 3-chlorophenylmercapto) diphenyl ether 4,4'-bis(3-chlorophenylmercapt0)diphenyl ether 3,3-bis(m-trifiuoromethylphenylmercapto)diphenyl ether 4,4'-bis(m-trifluoromethylphenylmercapto)diphenyl ether 3,4'-bis(m-trifiuoromethylphenylmercapto) diphenyl ether 2 ,3 -bis m-trifluoromethylphenylmercapto diphenyl ether 3,3'-bis(p-trifiuorornethylphenylmercapto) diphenyl ether 3,3'-bis(o-trifluoromethylphenylmercapto)diphenyl ether 3,3'-bis (m-methoxyphenylmercapto) diphenyl ether 3,4-bis(m-isopropoxyphenylmercapto)diphenyl ether 3,4-bis(rn-perfluorobutylphenylmercapto)diphenyl ether 2-(m-tolyloxy)-2'-phenylmercaptodiphenyl sulfide 2-(p-tolyloxy)-3'-phenylrnercaptodiphenyl sulfide 2-(o-tolyloxy)-4'-phenylmercaptodiphcnyl sulfide 3-(m-tolyloxy)-3'-phenylmercaptodiphenyl sulfide 3-(m-tolyloxy)-4'-phenylmercaptodiphenyl sulfide 4- m-tolyloxy -4'-phenylmercaptodiphenyl sulfide 3-xylyloxy-4'-phenylmercaptodiphenyl sulfide 3-xylyloxy- '-phenylmercaptodiphenyl sulfide 3-phenoxy3'-(mtolylmercapto)diphenyl sulfide 3-phenoxy-4'- (rn-tolylmercapto diphenyl sulfide 2-phenoxy-3'-(p-tolylmercapto)diphenyl sulfide 3-phenoxy-4'- (m-isopropylpheuylmercapto diphenyl sulfide 3-phenoxy-3'-(m-isopropylphenylmercapto)diphenyl sulfide 3-rn-toloxy-3'-(m-isopropylphenylrnercapto)diphenyl sulfide 4-(m-trifiuoromethylphenoxy)-4'-phenylmercaptodiphenyl sulfide 3-(m-trifluoromethylphenoxy)-4-phenylmercaptodiphenyl sulfide 2-(m-trifiuoromethylphenoxy)-3'-phenylmercaptodiphenyl sulfide 3 (m-trifluoromethylphenoxy) -3 '-phenylmercaptodiphenyl sulfide 3 (p-chlorophenoxy -3 -pheny1mercaptodiphenyl sulfide 3-(m-bromophenoxy)-4'-phenylmercaptodiphenyl sulfide bis [m-(m-chlorophenoxy)phenyl] sulfide m-bis [3-(p-methylphenylmercapto)phenoxy]benzene m-bis [3- (m-trifluoromethylphenoxy phenylmercapto] benzene m-bis[3-(m-bromophenoxy)phenylmercapto1benzene 3,3 '-bis [m- (p-methylphenylmercapto phenoxy diphenyl sulfide 3 ,4'-bis[mp-methylphenylmercapto phenoxy] diphenyl sulfide 3-(p-xenyloxy)-3'-phenylmercapto diphenyl sulfide,

and the like and mixtures thereof. It is also contemplated within the scope of this invention to employ m'nttures of polyphenyl ether-thioethers as base stocks.

The boron compounds useful in the compositions of this invention are well known to the art and can be prepared by distillation of diphenylborinic acids which in turn are prepared by the process set forth in an article by R. L. Letsinger et al., J. Am. Chem. Soc., 77, 2491 (1955).

The following examples serve to further illustrate the invention. All parts are parts by weight unless otherwise expressly set forth.

EXAMPLE A polyphenyl thioether-polyphenyl ether-thioether lubricant composition is prepared by combining 0.10 g. of diphenylborinic anhydride with 100 grams of a thioether of the following composition:

Percent by weight m-Bis(phenylmercapto benzene 5 O Bis(m-phenoxyphenyl) sulfide 12.5 (m-Phenoxyphenyl) (m-phenylmercaptophenyi sulfide 23 .5

Bis(m-phenylmercaptophenyl) sulfide 12.65 3 ring and 5 ring thioethers 1.35

and containing parts per million of a dimethyl silicone antifoam agent (Dow-Corning--200, 350 cs. fluid). After stirring at 40 C. to dissolve the anhydride, the mixture is cooled to room temperature and filtered. A lubricant composition without boron additives is used as control.

The useful life of a functional fluid can be determined on the basis of many criteria such as the extent of viscosity increase (oxidative stability) and corrosiveness toward metals under the conditions of use. The major bench scale method used for evaluating the oxidative stability of a functional fluid is the procedure given in Federal Test Specification 791, Method 5308 according to which the lubricant composition is heated at a specified temperature in the presence of certain metals and oxygen and the viscosity increase of the lubricant is determined.

The compositions of this example were tested according to the procedure of Federal Test Specification 791, Method 5308, i.e., 500 F. for 48 hours with five liters/ hour of air in the presence of steel, copper, silver, titanium, magnesium alloy and aluminum alloy. Information with respect to corrosiveness of the compositions to metals was also obtained. However, only the results upon copper and silver are reported since all the compositions tested had essentially no effect on the other metals employed. Viscosity measurements were made according to ASTM Method D-445-53T using a Cannon-Fenske modified Ostwald viscosimeter. The control base fluid ether and the compositions of this invention exhibited substantially the same viscosity increase. The corrosiveness to metals was determined by weighing metal specimens of known size before and after the test. Results and further details are given in the table below.

From the above it is clearly evident that the compositions of this invention exhibit markedly reduced corrosivity toward metals with no loss of oxidative stability and therefore have an extended useful life.

It will be appreciated that the compositions of the invention may also contain other additives, such as oxidation inhibitors, rust and corrosion inhibitors, antifoaming agents, detergents, viscosity index improvers such as polymeric materials for example, polyacrylate alkyl esters, polymethacrylate alkyl esters polyoxyalkylene compounds, polyurethanes and the like. Such additives are usually employed in amounts as low as 10 parts per million for antifoaming agent to as much as 15 parts by weight of the total compositions for viscosity index improvers.

While this invention has been described with respect to specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows:

1. Composition consisting essentially of a major amount of base fluid selected from the group consisting of polyphenyl thioethers, polyphenyl ether-thioethers, and mixtures thereof having the formula wherein R is phenyl, alkyl-substituted phenyl wherein the alkyl is of not more than 4 carbon atoms, alkoxy-substituted phenyl wherein the alkoxy is of not more than 4 carbon atoms or halogenated phenyl wherein the halogen is bromine, fluorine or chlorine, R is phenylene, alkyl or alkoxy-substituted phenylene wherein the alkyl contains no more than 4 carbon atoms or halogenated phenylene. wherein the halogen is fluorine, bromine or chlorine, and Y is selected from oxygen and sulfur but at least one of the Ys is sulfur and a is an integer having a value of 1 to 6 and a corrosion inhibiting amount of at least one diphenylborinic anhydride of the formula wherein R is alkyl of no more than 4 carbon atoms, halogen selected from Cl, Br and F, alkoxy of not more than 4 carbon atoms, haloalkyl of not more than 4 carbon atoms and 3 halogen atoms selected from Cl, Br and F, haloalkoxy of not more than 4 carbon atoms and 3 halogen atoms selected from Cl, Br and F, phenoxy, phenylmercapto or N0 R is halogen selected from Cl, Br and F or alkyl of not more than 4 carbon atoms, n is an integer of 0 to 3 and m is an integer of 0 to 2.

2. Composition of Claim 1 wherein the anhydride is present in an amount from about 0.01% to about 1.5% by Weight based on the total composition.

3. Composition of claim 1 wherein n is zero.

4. Composition of claim 1 wherein m is zero.

5. Composition of claim 1 wherein R is alkyl and m is zero.

6. Composition of claim 1 wherein R is haloalkyl and m is zero.

7. Composition of claim 1 wherein R is phenyl and R is phenylene.

8. Composition of claim 1 wherein R is haloalkyl and R is halogen.

diphenylborinic anhydride.

7 8 9. Composition of claim 1 wherein the anhydride is 3,450,770 6/1969 Campbell et a1 25278 X 3,455,846 7/1969 Bannister 25278 X References Cited UNITED OTHER REFERENCES STATES PATENTS 5 Chemical Abstracts," vol. 59, 8772(c) (1963).

Clayton et a1 2S275 LEON D. ROSDOL, Primary Examiner Dadura et a1 25 2-463 Gieseking 252 78 X H. A. PITLICK, Assistant Examiner Campbell et a1. 252-78 X Kay et a1 25249.6 10 US Campbell 252 78 X 25246.3, 49.6, 389 R; 26(]545, 606.5 B 

